Reconfigurable antennas are antennas that can dynamically modify their frequency band, radiation pattern, polarization, and/or gain properties in a controlled and reversible manner, and have applications in the fields of cellular radio communications, geolocation, radar (ground, airplane, and unmanned airborne vehicle), smart weapons, etc. Of particular interest to the present disclosure are reconfigurable antennas that can dynamically modify its radiation pattern, e.g., by steering a radiation beam or changing the width of the beam.
Phased array antennas may be utilized to electronically steer a radiation beam through different angles, typically in the range of 60 degrees from the normal direction of the fixed physical array. Phased array antennas require that each element in the antenna array have an independent antenna element and radio frequency (RF) circuits that are aggregated to provide the overall antenna directivity, thereby creating an N-factor constraint that dictates a significant cost and power consumption penalty. Additionally, this N-factor constraint places significant circuit complexity on the antenna array, which limits production yield and operational reliability.
A simpler approach employs a mechanically articulatable antenna that includes a mechanical platform that physically moves or tilts the antenna unit to steer a radiation beam through different angles, typically in a range as much as ±90 degrees. Due to its simple electrical design, which requires only one antenna element, the N-factor constraint typically imposed on phased array antennas is avoided. However, mechanically articulatable antennas are typically slow in articulation, require moving parts that are subject to degradation, are physically very large and heavy, and are relatively expensive, thereby limiting the application of this technology.
Lens-based antenna approaches offer a viable and lower cost alternative to phased array and mechanically articulable antennas. For example, in one embodiment, multiple antenna feed elements can be placed around a spherical dielectric lens and selectively switched on and off to produce a wide field of beam coverage that avoids some of the engineering issues of phased array and mechanically articulatable antennas. However, although less technically complex than phased array antennas, reconfigurable lens-based antennas require multiple antenna feed elements and associated switches, and thus, still suffer from an N-factor constraint in terms of weight, power, size, and cost.
Of particular interest to the present disclosure are the switches used to selectively turn the antenna feed elements on and off. Various types of conventional switches that can be used for the antenna feed elements include servo-mechanical switches, ferrite switches, and pin-diode switches. Servo-mechanical switches are relatively slow, typically having switch speeds on the order of 10−3 seconds (or several kilohertz). Ferrite switches require a relatively large amount of power to operate. Pin-diode switches are relatively complicated and expensive. All known conventional switches, including servo-mechanical switches, ferrite switches, and pin-diode switches, require some type of transition from the antenna feed element to a board or to a connector, thereby introducing insertion losses and additional design complexity into the reconfigurable antenna design.
There, thus, remains a need for an improved mechanism for selectively switching antenna feed elements in a reconfigurable antenna.